This is a completely new project, the result of a long development from the Beta R&D department and aimed at filling a gap in the off road market as a play bike, but also a serious race bike for the newly created GNCC XC3 class as well as the NEPG Enduro classes.

Engine
This is the smallest 2-stroke engine of the Enduro range currently produced at Beta's factory in Italy. The result of a long process of design and development, carried out entirely by the Technical and R&D Departments with the focus being a proper engine layout designed to optimize the distribution of weight while paying close attention to the power delivery. The result of the engine's components including the crankshaft and gearbox, has created a compact engine that provides the optimum performance and reliability. The power delivery is smooth, yet powerful which is a feature not found in many models this size.

There are many distinctive features of this engine, including:

Double piston rings (54 mm): piston designed to ensure high rigidity and reliability; the choice of double rings provides a better seal at the low and medium rpm ranges typical of off road riding.
Beta progressive valve: the power valve system derived from the 250 and 300cc RR models, characterized by a particular relationship between the opening of the main flap and that of the side boosters. The delay in opening the boosters enables excellent progressiveness in performance throughout the rpm range of the engine.
Crankshaft with polyamide inserts: favoring lightness and ensuring optimum filling of the crankcase to the benefit of performance and reliability.
Cylinder: exhaust flange system that is a separate machined part like that on the larger 2018 RR models, enabling better control of the piston-flap-cylinder front tolerance. By keeping this value to a minimum it is possible to achieve a significant performance boost at low rpm, reducing the leakage of gases.

Removable cylinder head dome: rigid and lightweight, made possible by moving the engine coupling on the cylinder. The geometry of the combustion chamber is designed to provide the best compromise between responsiveness at low-to-medium revs and top end power delivery. It also facilitates the fine tuning and replacement of the combustion chamber.
Die-cast aluminum crankcase: the casing geometries were designed according to an innovative layout in terms of the relative position of components and with a view to maximum weight reduction without compromising structural strength. The main bearing area received particular attention to ensure the correct rigidity of the walls in order to withstand the stresses transmitted by the crankshaft.

Die-cast clutch and ignition covers in magnesium: ensuring very low weight and optimal surface finish. It was possible to also adopt this solution for the inner clutch cover thanks to the isolation of the water pump from this element.
V-force4 reed valve assembly: the presence of the stoppers ensures high reliability without compromising performance. Provides stronger low-end power output.
Pre-mix: to keep the weight of the bike low.
6-speed dog-box transmission: specially developed for this engine with gears made by mechanical machining of blanks, forged so as to provide mechanical strength and reliability while still maintaining very light and compact gearbox.
Clutch: multi-disc in oil bath with reverse opening, unlike the larger RR's, this clutch actuator is integrated in the outer cover. This is a system designed for maximum lightness and compactness of the engine which, thanks to its low positioning, ensures the reduced size of the power unit and a significant centralization of weight.

Electric starter-ready: Beta has designed the 125 engine to accept, as an accessory an electric start system for those wanting a push button start.

Chassis
The chassis derives partly from the 250/300 RR but was developed specifically to optimize the behavior of the engine-frame combination. The frame, in chrome molybdenum with double cradle split above the exhaust port, has been redesigned for a small engine, revising its principal dimensions and ensuring an optimal positioning of the engine.This solution has allowed particular characteristics of the RR family to be further enhanced, such as its great maneuverability and ridability - even more noticeable due to the low weight of the motorcycle - as well as stability.

Among the many innovations adopted on this model are:

Geometry of the new upper engine head stay: various solutions were researched and developed before the final one that made it possible to reduce the vibrations generated by the engine while maintaining significant engine-frame system stiffness.
Sachs Suspension: derived from the rest of the RR range but with its own settings. At the front there is an open-cartridge fork of 48 mm diameter.
Exhaust system: in order to optimize the 2-stroke engine's torque and power curves, the Beta R&D Department has developed a special system dedicated to Enduro use.
Filter box sleeve: designed for the 125 cc engine, it improves the flow across the range of operation, from low revs upwards.
Engine guard: made from polyamide to combine strength and lightness, it provides excellent shielding against the ingress of mud between the engine and the guard.
Fuel tank: a slightly smaller tank has been adopted to improve ergonomics on board the bike while maintaining sufficient fuel mileage.
Cooling system: designed especially for this bike, it has new hoses and radiators with specially shaped reservoirs to fit the small size of the motorcycle.
Nissin braking system: extremely powerful and configurable, the same as on the rest of the Enduro range.
Colors and graphics: the same as the rest of the RR my 2018 range.

Happy to see new 125's coming out :D I have also heard Beta has a 200 in the pipeline.

Wonder how much the e-start add on will be? Weight with and without? Probably a close ratio trans like my Husky which is less than fun off of a race course. Also a bit of a bummer for no OI or DI as that is one of the biggest things that would push me to buy something new.

Yep, leaving off the convenience items off probably indicates a more race focused bike. Gotta have a bike for the teenagers and twenty-somethings to go nuts on.

I could probably do with spending some time on a 125 to get better with maintaining momentum off road. In a similar way riding the wr250x on the street is so much different from even the versys (which is not a powerful bike, ~60 hp). I do like that I don't have to slow down at all for corners but I'm no good at keeping the speed up through the exit yet.